In a hospital setting, medical staff is constantly removing medical supplies from a supply cabinet and placing new supplies back in the cabinet. It is a common practice to use some type of automation to track items in the inventory of the medical supply cabinet.
For example, in some systems referred to as “Push-to-Take” systems, a medical personnel touches either a “store” or “remove” button located on the front of a medical cabinet storage slot to indicate to an inventory tracking system whether an item in that storage slot is being removed or added to the inventory. The tracking system updates the inventory based on the input received from these button presses.
In practice, a Push-to-Take system suffers from several drawbacks. The system primarily relies on a human user to correctly note each removal or addition of an inventory item. This could result in erroneous inventory tracking resulting from human errors. Secondly, when adding/removing multiple inventory items from the same storage slot, the system requires the human user to press the store/remove button multiple times. A mismatch between the number of items and the number of key presses is another potential source of error in the system. The system also breaks workflow continuity of the medical personnel because instead of simply opening the cabinet door and placing new items in a storage bin or removing items from a storage bin, the user now has to stop and press buttons the correct number of times. Furthermore, when multiple inventory items of the same type with different lot and serial numbers are stored, a user must enter the lot and serial number information for each item at load time and select which particular item was removed at the time of taking the item out.
In another inventory tracking system, each item in the storage is tagged with a unique radio frequency (RF) tag. When the door to a medical cabinet is in the closed position, the inventory tracking system performs an RF scan of the cabinet to detect the items currently present in the cabinet. The inventory tracking system then compares the results of this detection with previous results to decide which items were added to the cabinet and which items were removed from the cabinet. This system is sometimes referred to as an “All Cabinet Scan” system.
In practice, an All Cabinet Scan system has certain shortcomings. For example, the cabinet scan can sometimes miss inventory items. This can happen, for example, if one inventory item is occluded by another inventory item. Furthermore, an All Cabinet Scan system may be “spoofed” by a user accidentally or intentionally holding an inventory item in proximity of a closed cabinet door so that the RF scanning counts the item as being in the inventory. To avoid such “spoofing,” the scanning process may be designed to be less sensitive to inventory items present near the cabinet door area. However, this limits the available storage space for the cabinet. Another shortcoming of the All Cabinet Scan is that for low error scanning, high power RF transmissions are needed. Thus, an All Cabinet Scan system is a large power consumer. Also, to keep the RF transmissions of the scanner from interfering with other radiation-sensitive equipment around the cabinet, the cabinet may have to be fitted with expensive electromagnetic shielding such as a Faraday cage. Another disadvantage of the All Cabinet Scan system is that the RF transmissions of the scanner could potentially harm RF-sensitive medical devices (e.g., pacemakers) that need to be stored inside the medical cabinet. Also, because the All Cabinet Scan system performs inventory check after the cabinet door is closed, it cannot immediately notify a user if the user takes out an expired medication item.